Many wireless mobile companies "round-up" to the closest megabyte. Meaning every time you hit your phone's web browser, you're using a baseline of 1 MB of that 200 MB maximum.
Let me show you something. I'm a complete and total geek, and I thought this was kind of interesting - my T-Mobile smart phone was more or less abandoned for the past five days as I was taking final exams, writing term papers and doing everything except using my phone. All I used the phone for was occasionally reading email that is downloaded to my phone - I wasn't going online for anything. I have an unlimited data plan, so I don't pay for overages, but T-Mobile clearly states at the top of this information page: "For billing, data is rounded up to the nearest MB." So if I was paying per megabyte, this would add up to several hundred megabytes of data, even though all I actually used was .00002 something percent of a megabyte. You can in this way easily and very quickly reach 200 MB+ and start going over your limit. This "rounding-up policy" is standard for most mobile phone companies, and I was billed for data usage (although like I said, not charged, since I have an unlimited data plan) every time the phone automatically retrieved my email for the five days that I didn't actually use my phone. The data usage looked like this for the five days, with probably ten pages of numbers filling the screen:
05/30/1111:27 PM0.075105/30/1109:27 PM0.030205/30/1107:27 PM0.010705/30/1105:27 PM0.054605/30/1104:23 PM0.001905/30/1102:23 PM0.197205/30/1101:14 PM0.091705/30/1111:14 AM0.025305/30/1110:27 AM0.011705/30/1108:27 AM0.178705/30/1106:27 AM0.1162
Another thing you need to be aware of: most mobile phone companies (who seem to have no trouble at all billing correctly for phone calls made) swear that they have no way of giving customers an accurate, up-to-the hour record of their data usage. Sometimes it takes days or even weeks for the usage to catch up to the billing records, and I have known people who relied on what information they found in their online records to monitor their data usage, thinking they were within their plan range, and then boom! all of a sudden, there's a bill for $3000 of data overages in their mailbox. So you are right to be a little paranoid about going over your 200 MB of data per month.
